Fluid streams comprise a mobile phase and an entrained particle or particulate. Such streams are often combined or contaminated with substantial proportions of one or more liquid or solid particulate materials. These contaminant materials can vary in composition, particle size, particle morphology, density or other physical parameters. The fluid may be air, and air streams can be filtered in intake streams in the cabins of motorized vehicles, air in computer disk drives, HVAC air clean room ventilation and applications using filter bags, barrier fabrics, woven materials, air to engines for motorized vehicles or for power generation. Alternatively, filtration can be employed for gas streams directed to gas turbines or air streams used in a variety of combustion furnaces.
Polymer webs have been made by electrospinning, extrusion melt spinning, air laid processes or wet laid processing. The manufacture of filter structures from filter media is well known and has been practiced for many years. The filtration efficiency of such filters is characteristic of the filtration media and is related to the fraction of the particulate removed from the mobile fluid stream. Efficiency is typically measured by a set test protocol, an example of which is defined below. Fine fiber technologies that contemplate polymeric materials blended with a variety of other substances is disclosed in Chung et al., U.S. Pat. No. 6,743,273; Chung et al., U.S. Pat. No. 6,924,028; Chung et al., U.S. Pat. No. 6,955,775; Chung et al., U.S. Pat. No. 7,070,640; Chung et al., U.S. Pat. No. 7,090,715; Chung et al., U.S. Patent Publication No. 2003/0106294; Barris et al., U.S. Pat. No. 6,800,117; and Gillingham et al., U.S. Pat. No. 6,673,136. Additionally, in copending U.S. Ser. No. 11/272,492 filed 10 Nov. 2005, a water insoluble, high strength polymer material is made by blending a polysulfone polymer with a polyvinylpyrrolidone polymer resulting in a single phase polymer alloy used in electrospinning fine fiber materials. While the fine fiber materials discussed above have adequate performance for a number of filtration end uses, in applications with extremes of temperature ranges, where mechanical stability is required, improvements in fiber properties can always be made.